EFFECTS OF DRIED DISTILLERS GRAINS WITH SOLUBLES (DDGS) FEEDING STRATEGIES ON GROWTH PERFORMANCE, NUTRIENT INTAKE, BODY COMPOSITION, AND LEAN AND FAT QUALITY OF IMMUNOLOGICALLY CASTRATED PIGS HARVESTED AT 5, 7, or 9 WEEKS AFTER THE SECOND IMPROVEST® DOSE A DISSERTATION SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY Erin Kay Harris IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Gerald C. Shurson, Adviser December 2014 © Erin K. Harris 2014 Acknowledgements This thesis could not have been completed without the support and help of many people. My love for agriculture, food-producing animals, and pigs is only possible due to the enormous gift and blessing of growing up on a hog farm, where my early days included the stroller view of the farrowing barn and paint-stick wall art in the finishing barn. My parent’s dedication and perseverance through many challenges I’ve experienced are a gift, and provided me with perspective and instilled my core values. In addition, I could not have accomplished this without the left over meals from my mother and pep- talks from my father, who's first-hand experience of the Ph.D. process was invaluable and is an experience that few fathers anddaughters can relate. To my committee members, Dr. Jerry Shurson, Dr. Lee Johnston, Dr. Bill Dayton, Dr. Ryan Cox, and Dr. Marnie Mellencamp, thank-you for taking me on as graduate student, and providing opportunities to allow me to develop into a more well-rounded professional, and for challenging me outside of my academic comfort zone. I also appreciate your encouragement of my involvement in the pork industry. To Dr. Pedro Urriola, my sincerest thanks for sharing your knowledge, experiences, brainstorming sessions, the many two-minute conversations that turned into 60+ minute conversations about swine nutrition, pigs, research, and career. Your addition to the swine nutrition group has been invaluable and I appreciate your guidance, especially through the preliminary exam process. I thank Dr. William Dayton, Dr. Marcia Hathaway, and Dr. Mike White in the Growth Biology Laboratory for teaching me molecular biology techniques and providing an environment where I was comfortable asking countless questions. To Dr. Ryan Cox, I thoroughly appreciate staying connected and involved with i the meat science crew, and I appreciate the assistance from Mr. Pete Nelson, Mr. Tristan McNamara, Mr. Dallas Dornink, Dr. Kaitlyn Compart, and Mr. Justin Johnston and all undergraduate meat lab workers, and being so accommodating and patient with this intensive project. To my fellow swine group graduate students past and present, thank you for your generosity of time and willingness to help on such an extensive research project. This research would not have been possible without you. Thank you for pitching in and helping when needed, and of equal or greater importance, helping me through the ups and downs of graduate school, celebrating the highs, and lending an ear during the lows. Particularly I would like to thank Dr. Kaitlyn Compart, Ms. Brenda Reiter, Dr. Emily Glunk, Ms. Gail Carpenter, Dr. Devan Paulus Compart, Ms. Elizabeth Bjorklund, Mr. Sam Fessenden, Ms. Amy Hazel, Mr. Justin Johnston, and Mr. Isaac Salfer. Additionally, I would like to thank all of my other friends spread across the country for your support and understanding, especially Ms. Faith Wentzel, Ms. Erika Dyk, and Ms. Andrea Marihart. Still none of this would have been possible without the hard work of the staff at the West Central Research and Outreach Center. Thank you to all Farm Animal Attendants, Mr. Mark Smith, and Ms. Adrienne Hilbrands for all of your hard work in the daily care of pigs in this project and all of the other research projects. Additionally, I would like to thank Dr. Jon Anderson for his statistical analysis expertise and advice. Last, but not certainly not least, many thanks to Zoetis, Inc for providing funding for this research and I would like to express my gratitude particularly to Dr. Marnie ii Mellencamp and Dr. Christi Calhoun. It has been a pleasure working with you and I truly appreciate your guidance and mentorship as professional women in animal science. iii Table of Contents Acknowledgements ............................................................................................................ i Table of Contents ............................................................................................................. iv List of Tables .................................................................................................................... xi List of Figures ................................................................................................................ xvii CHAPTER 1: Introduction and literature review ......................................................... 1 I. Introduction .................................................................................................................. 1 II. Physiological comparison of gilts, physically castrated, and intact male pigs ........... 7 A. Hormonal profile .................................................................................................... 7 B. Nutritional requirements to maximize lean and minimize adipose accretion ....... 10 C. Feed intake regulation ........................................................................................... 14 III. Limitations of growing intact male pigs in U.S. pork production systems ............. 16 A. Boar taint .............................................................................................................. 17 1. The role of androstenone and skatole ................................................................ 17 2. Chemical prevalence and sensory detection of boar taint ................................. 21 IV. Methods to overcome the limitations of intact males in pork production .............. 24 A. Market at lighter body weight ............................................................................... 25 B. Genetics................................................................................................................. 26 C. Diet ........................................................................................................................ 26 D. Environment ......................................................................................................... 29 E. Immunological castration ...................................................................................... 30 V. Benefits and limitations of immunological castration .............................................. 31 A. Physiological changes following the first Improvest® dose ................................ 31 B. Physiological changes following the second Improvest® dose ............................ 32 C. Growth performance ............................................................................................. 35 1. Average daily feed intake after the second Improvest® dose ............................ 35 2. Average daily gain and feed efficiency after the second Improvest® dose ....... 37 3. Overall growth performance.............................................................................. 37 4. Future understanding of feed intake in immunologically castrated pigs .......... 39 iv D. Environmental impact ........................................................................................... 40 E. Carcass components .............................................................................................. 41 1. Carcass dressing percentage ............................................................................. 41 2. Carcass lean and fat .......................................................................................... 43 3. Carcass primal cut composition ........................................................................ 49 a. Ham, shoulder, and loin primal cuts ............................................................... 50 b. Belly primal cut .............................................................................................. 51 F. Considerations for carcass lean and fat quality ..................................................... 52 1. Animal behavior and premortem handling ........................................................ 52 2. Lean composition and quality ............................................................................ 54 3. Pork fat quality .................................................................................................. 58 a. Changing consumer preferences for fat .......................................................... 58 b. Assessment of pork fat quality ....................................................................... 58 c. Fatty acid compositional differences among depots ...................................... 62 1. Classes and functions of lipids ................................................................... 63 2. Fatty acid content of longissimus muscle vs. subcutaneous fat .................. 63 3. Fatty acid composition differences among fat depots ................................ 64 4. Fatty acid composition differences among subcutaneous depots ............... 65 5. Fatty acid concentration differences within fat depot location .................. 65 d. Carcass fat characteristics among sexes ......................................................... 66 e. Consequences of soft pork fat .......................................................................